519 lines
12 KiB
Markdown
519 lines
12 KiB
Markdown
# yargs-parser
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[](https://www.npmjs.com/package/yargs-parser)
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[](https://conventionalcommits.org)
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The mighty option parser used by [yargs](https://github.com/yargs/yargs).
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visit the [yargs website](http://yargs.js.org/) for more examples, and thorough usage instructions.
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<img width="250" src="https://raw.githubusercontent.com/yargs/yargs-parser/main/yargs-logo.png">
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## Example
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```sh
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npm i yargs-parser --save
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```
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```js
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const argv = require('yargs-parser')(process.argv.slice(2))
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console.log(argv)
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```
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```console
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$ node example.js --foo=33 --bar hello
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{ _: [], foo: 33, bar: 'hello' }
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```
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_or parse a string!_
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```js
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const argv = require('yargs-parser')('--foo=99 --bar=33')
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console.log(argv)
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```
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```console
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{ _: [], foo: 99, bar: 33 }
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```
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Convert an array of mixed types before passing to `yargs-parser`:
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```js
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const parse = require('yargs-parser')
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parse(['-f', 11, '--zoom', 55].join(' ')) // <-- array to string
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parse(['-f', 11, '--zoom', 55].map(String)) // <-- array of strings
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```
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## Deno Example
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As of `v19` `yargs-parser` supports [Deno](https://github.com/denoland/deno):
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```typescript
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import parser from "https://deno.land/x/yargs_parser/deno.ts";
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const argv = parser('--foo=99 --bar=9987930', {
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string: ['bar']
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})
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console.log(argv)
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```
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## ESM Example
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As of `v19` `yargs-parser` supports ESM (_both in Node.js and in the browser_):
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**Node.js:**
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```js
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import parser from 'yargs-parser'
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const argv = parser('--foo=99 --bar=9987930', {
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string: ['bar']
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})
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console.log(argv)
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```
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**Browsers:**
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```html
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<!doctype html>
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<body>
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<script type="module">
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import parser from "https://unpkg.com/yargs-parser@19.0.0/browser.js";
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const argv = parser('--foo=99 --bar=9987930', {
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string: ['bar']
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})
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console.log(argv)
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</script>
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</body>
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```
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## API
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### parser(args, opts={})
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Parses command line arguments returning a simple mapping of keys and values.
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**expects:**
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* `args`: a string or array of strings representing the options to parse.
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* `opts`: provide a set of hints indicating how `args` should be parsed:
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* `opts.alias`: an object representing the set of aliases for a key: `{alias: {foo: ['f']}}`.
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* `opts.array`: indicate that keys should be parsed as an array: `{array: ['foo', 'bar']}`.<br>
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Indicate that keys should be parsed as an array and coerced to booleans / numbers:<br>
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`{array: [{ key: 'foo', boolean: true }, {key: 'bar', number: true}]}`.
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* `opts.boolean`: arguments should be parsed as booleans: `{boolean: ['x', 'y']}`.
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* `opts.coerce`: provide a custom synchronous function that returns a coerced value from the argument provided
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(or throws an error). For arrays the function is called only once for the entire array:<br>
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`{coerce: {foo: function (arg) {return modifiedArg}}}`.
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* `opts.config`: indicate a key that represents a path to a configuration file (this file will be loaded and parsed).
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* `opts.configObjects`: configuration objects to parse, their properties will be set as arguments:<br>
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`{configObjects: [{'x': 5, 'y': 33}, {'z': 44}]}`.
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* `opts.configuration`: provide configuration options to the yargs-parser (see: [configuration](#configuration)).
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* `opts.count`: indicate a key that should be used as a counter, e.g., `-vvv` = `{v: 3}`.
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* `opts.default`: provide default values for keys: `{default: {x: 33, y: 'hello world!'}}`.
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* `opts.envPrefix`: environment variables (`process.env`) with the prefix provided should be parsed.
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* `opts.narg`: specify that a key requires `n` arguments: `{narg: {x: 2}}`.
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* `opts.normalize`: `path.normalize()` will be applied to values set to this key.
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* `opts.number`: keys should be treated as numbers.
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* `opts.string`: keys should be treated as strings (even if they resemble a number `-x 33`).
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**returns:**
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* `obj`: an object representing the parsed value of `args`
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* `key/value`: key value pairs for each argument and their aliases.
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* `_`: an array representing the positional arguments.
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* [optional] `--`: an array with arguments after the end-of-options flag `--`.
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### require('yargs-parser').detailed(args, opts={})
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Parses a command line string, returning detailed information required by the
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yargs engine.
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**expects:**
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* `args`: a string or array of strings representing options to parse.
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* `opts`: provide a set of hints indicating how `args`, inputs are identical to `require('yargs-parser')(args, opts={})`.
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**returns:**
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* `argv`: an object representing the parsed value of `args`
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* `key/value`: key value pairs for each argument and their aliases.
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* `_`: an array representing the positional arguments.
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* [optional] `--`: an array with arguments after the end-of-options flag `--`.
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* `error`: populated with an error object if an exception occurred during parsing.
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* `aliases`: the inferred list of aliases built by combining lists in `opts.alias`.
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* `newAliases`: any new aliases added via camel-case expansion:
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* `boolean`: `{ fooBar: true }`
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* `defaulted`: any new argument created by `opts.default`, no aliases included.
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* `boolean`: `{ foo: true }`
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* `configuration`: given by default settings and `opts.configuration`.
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<a name="configuration"></a>
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### Configuration
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The yargs-parser applies several automated transformations on the keys provided
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in `args`. These features can be turned on and off using the `configuration` field
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of `opts`.
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```js
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var parsed = parser(['--no-dice'], {
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configuration: {
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'boolean-negation': false
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}
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})
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```
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### short option groups
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* default: `true`.
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* key: `short-option-groups`.
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Should a group of short-options be treated as boolean flags?
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```console
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$ node example.js -abc
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{ _: [], a: true, b: true, c: true }
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```
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_if disabled:_
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```console
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$ node example.js -abc
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{ _: [], abc: true }
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```
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### camel-case expansion
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* default: `true`.
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* key: `camel-case-expansion`.
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Should hyphenated arguments be expanded into camel-case aliases?
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```console
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$ node example.js --foo-bar
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{ _: [], 'foo-bar': true, fooBar: true }
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```
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_if disabled:_
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```console
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$ node example.js --foo-bar
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{ _: [], 'foo-bar': true }
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```
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### dot-notation
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* default: `true`
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* key: `dot-notation`
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Should keys that contain `.` be treated as objects?
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```console
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$ node example.js --foo.bar
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{ _: [], foo: { bar: true } }
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```
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_if disabled:_
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```console
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$ node example.js --foo.bar
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{ _: [], "foo.bar": true }
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```
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### parse numbers
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* default: `true`
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* key: `parse-numbers`
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Should keys that look like numbers be treated as such?
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```console
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$ node example.js --foo=99.3
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{ _: [], foo: 99.3 }
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```
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_if disabled:_
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```console
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$ node example.js --foo=99.3
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{ _: [], foo: "99.3" }
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```
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### parse positional numbers
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* default: `true`
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* key: `parse-positional-numbers`
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Should positional keys that look like numbers be treated as such.
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```console
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$ node example.js 99.3
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{ _: [99.3] }
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```
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_if disabled:_
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```console
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$ node example.js 99.3
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{ _: ['99.3'] }
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```
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### boolean negation
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* default: `true`
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* key: `boolean-negation`
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Should variables prefixed with `--no` be treated as negations?
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```console
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$ node example.js --no-foo
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{ _: [], foo: false }
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```
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_if disabled:_
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```console
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$ node example.js --no-foo
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{ _: [], "no-foo": true }
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```
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### combine arrays
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* default: `false`
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* key: `combine-arrays`
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Should arrays be combined when provided by both command line arguments and
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a configuration file.
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### duplicate arguments array
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* default: `true`
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* key: `duplicate-arguments-array`
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Should arguments be coerced into an array when duplicated:
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```console
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$ node example.js -x 1 -x 2
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{ _: [], x: [1, 2] }
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```
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_if disabled:_
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```console
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$ node example.js -x 1 -x 2
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{ _: [], x: 2 }
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```
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### flatten duplicate arrays
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* default: `true`
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* key: `flatten-duplicate-arrays`
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Should array arguments be coerced into a single array when duplicated:
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```console
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$ node example.js -x 1 2 -x 3 4
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{ _: [], x: [1, 2, 3, 4] }
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```
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_if disabled:_
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```console
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$ node example.js -x 1 2 -x 3 4
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{ _: [], x: [[1, 2], [3, 4]] }
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```
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### greedy arrays
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* default: `true`
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* key: `greedy-arrays`
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Should arrays consume more than one positional argument following their flag.
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```console
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$ node example --arr 1 2
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{ _: [], arr: [1, 2] }
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```
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_if disabled:_
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```console
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$ node example --arr 1 2
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{ _: [2], arr: [1] }
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```
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**Note: in `v18.0.0` we are considering defaulting greedy arrays to `false`.**
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### nargs eats options
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* default: `false`
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* key: `nargs-eats-options`
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Should nargs consume dash options as well as positional arguments.
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### negation prefix
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* default: `no-`
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* key: `negation-prefix`
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The prefix to use for negated boolean variables.
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```console
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$ node example.js --no-foo
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{ _: [], foo: false }
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```
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_if set to `quux`:_
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```console
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$ node example.js --quuxfoo
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{ _: [], foo: false }
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```
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### populate --
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* default: `false`.
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* key: `populate--`
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Should unparsed flags be stored in `--` or `_`.
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_If disabled:_
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```console
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$ node example.js a -b -- x y
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{ _: [ 'a', 'x', 'y' ], b: true }
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```
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_If enabled:_
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```console
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$ node example.js a -b -- x y
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{ _: [ 'a' ], '--': [ 'x', 'y' ], b: true }
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```
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### set placeholder key
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* default: `false`.
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* key: `set-placeholder-key`.
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Should a placeholder be added for keys not set via the corresponding CLI argument?
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_If disabled:_
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```console
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$ node example.js -a 1 -c 2
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{ _: [], a: 1, c: 2 }
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```
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_If enabled:_
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```console
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$ node example.js -a 1 -c 2
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{ _: [], a: 1, b: undefined, c: 2 }
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```
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### halt at non-option
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* default: `false`.
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* key: `halt-at-non-option`.
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Should parsing stop at the first positional argument? This is similar to how e.g. `ssh` parses its command line.
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_If disabled:_
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```console
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$ node example.js -a run b -x y
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{ _: [ 'b' ], a: 'run', x: 'y' }
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```
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_If enabled:_
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```console
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$ node example.js -a run b -x y
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{ _: [ 'b', '-x', 'y' ], a: 'run' }
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```
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### strip aliased
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* default: `false`
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* key: `strip-aliased`
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Should aliases be removed before returning results?
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_If disabled:_
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```console
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$ node example.js --test-field 1
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{ _: [], 'test-field': 1, testField: 1, 'test-alias': 1, testAlias: 1 }
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```
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_If enabled:_
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```console
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$ node example.js --test-field 1
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{ _: [], 'test-field': 1, testField: 1 }
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```
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### strip dashed
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* default: `false`
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* key: `strip-dashed`
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Should dashed keys be removed before returning results? This option has no effect if
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`camel-case-expansion` is disabled.
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_If disabled:_
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```console
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$ node example.js --test-field 1
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{ _: [], 'test-field': 1, testField: 1 }
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```
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_If enabled:_
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```console
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$ node example.js --test-field 1
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{ _: [], testField: 1 }
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```
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### unknown options as args
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* default: `false`
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* key: `unknown-options-as-args`
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Should unknown options be treated like regular arguments? An unknown option is one that is not
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configured in `opts`.
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_If disabled_
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```console
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$ node example.js --unknown-option --known-option 2 --string-option --unknown-option2
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{ _: [], unknownOption: true, knownOption: 2, stringOption: '', unknownOption2: true }
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```
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_If enabled_
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```console
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$ node example.js --unknown-option --known-option 2 --string-option --unknown-option2
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{ _: ['--unknown-option'], knownOption: 2, stringOption: '--unknown-option2' }
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```
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## Supported Node.js Versions
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Libraries in this ecosystem make a best effort to track
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[Node.js' release schedule](https://nodejs.org/en/about/releases/). Here's [a
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post on why we think this is important](https://medium.com/the-node-js-collection/maintainers-should-consider-following-node-js-release-schedule-ab08ed4de71a).
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## Special Thanks
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The yargs project evolves from optimist and minimist. It owes its
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existence to a lot of James Halliday's hard work. Thanks [substack](https://github.com/substack) **beep** **boop** \o/
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## License
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ISC
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